You're absolutely right that this is a dark pattern, but it's not a current one - it's the echo of the dark pattern we screwed up on last year. If you hid your profile at the time, prior to last year's thread and our response to it, the maximum duration was one year (and yes, this was a really terrible idea among the other really-terrible-ideas that were called out at the time). But we changed that last year during our internal response. Hiding your profile indefinitely on our current site does in fact hide it indefinitely, and has ever since it was added as an option. (see https://imgur.com/n5e4CMB - and just to be clear this is my personal prod-testing account, not an actual person whose profile I screenshotted)
What happened here is that if you had hidden your profile just before we added the indefinite option, you were caught by the old dark pattern, which only let you hide it for up to a year. (And so, a year later, we're correctly informing you that it is now visible again.) We fixed the site at the time so that no one would newly be caught in this pattern, but what we failed to do was retroactively change the setting for people who'd selected 'one year' prior to that point.
This was a genuine oversight, and we'll fix it. I need to speak to our engineering team to make sure we can actually do so, but my immediate plan is to effectively just make the indefinite hiding retroactive by assuming anyone who set it to the max last year wanted that. In any case, it will get fixed one way or another - I was as pissed as anyone here by last year's events and have no intention of leaving y'all high and dry.